SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7937cf4e43882db6009bc01d02e1ded60f19202325f20a27ec029e9948a0ef3d' 
  AND token = 'ekf0dJ4+mxPyI5EIWrqMMdZqvGbyDSNKjEtWgoyA9rw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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