SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '887a1eef3b9880435a1347cfb0d424dfaf52be6834117c5c82d6fb719bbfe508' 
  AND token = '50mC1QSztRsHyynSPHOyO38FLelyI9EcMesFwyDpqq0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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