SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6dcdd27a98a3cbbddd4640b87fc3f8ab300f6c05d57dab80b14f8b67f6377a3' 
  AND token = 'yLKfX+i2bLLGFnWvI6aqDIXEIjYnRXAMfmnADvqlZd8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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