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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd875b89e3add2cdf781ccd3f9ef251d9c018b0bfe76b7029fd13999196c5b7ac' 
  AND token = '1dmE+QRaLDY1eeRpkAYo+1mQIalvKM4spNPi/2jQ5og=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00009

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}