SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '24e239653b3e19660d53a99d39918ad16d77380fb07038249c05f546919ba8ae' 
  AND token = '1JRMPBWEH2JKo+16IlVqjJkq15tptYadDFhocEpdPj8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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