SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ecc15802119ded1e7b797be35858f334bf9fa6d8d14cea0af490a4455db2c456' 
  AND token = 'QGxNmzZLl0xZvhhzurN8nYe4eZLkf7gUPyatwpBvKdo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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