SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9be7558b14c0bf924499670572df68d62e38119ae502fd1db53fb6c260c861d5' 
  AND token = '3SaWPJpb+Azb2UQ68SElfBHuCRRCpNqe8lrp8XnjvV8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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