SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e2c4c6524eb8389e6733a052a218687c61a18c54f591365bbe0d8cb51106f200' 
  AND token = 'E9sqbWnWKfmR/vAnbkpWUnyPQdBx3eqWxZgopi+Hh30=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}