SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b531b4daf4ccd3461f754f75e413cc8d8c026400a10643be598ecfdd1a5ab443' 
  AND token = 'Qg8twk7Oz/MHLhs6Y6ovp7xsqhzdyhW6wbs6zRE5oyc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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