SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '20e5d719a433c031cf84edab79dde61883bb1a469fb91b3970c9be4a4af26470' 
  AND token = 'M/KQ+PCDTyQu3Qo8vyIKKs0jydjMi2eC3jEPwOhHYRA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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