SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e98cbb16fbc5a4569aed7251254b42b76a693ac3c963185ff78129396e55d0f3' 
  AND token = 'm6c9Mmon1siW55kIEmlMWC4J9dt6Fgf9NwLLC+2es58=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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