SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8466c523ac78c510397b3901b9ab8159699923e4cc845844cdf096b7932826bf' 
  AND token = 'zP7bhjSftInOj+9QxAmoTbo6twL7l8kEp7smU8nMco0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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