SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '03257cf8b771f847efde9acbd14c79857cf9247c8aa689ba56b4d4520bdb6704' 
  AND token = 'OXX9b48HGRTJjV2B9lTF0pjfnVWKUXDRFmKuBIjaVjs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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