SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f34591bc6f5ced4aeb2897c77efc2594557d72d4d59e84f4464b4459cfedef6b' 
  AND token = 'RBRoiYFdpRdQyG8MmrqhH/cmt+LsALWu/Lb0RcMmFrk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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