SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f77857983b7be812df3f93a75fa660df6613c6de53500c460edd6897cb93ab2a' 
  AND token = 'n2DbFbPok7kVsuB/92PN0LYvel/eqxHffLmbcKasueg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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