SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '5947ce5a1552bd84d80d35673612435b293e3b3c9176463dc279f4d7a3aa7446' 
  AND token = 'mMXzTpo4DwRBzNNGdKr3NSzfs3rC488rajNMaMRH35E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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