SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '73cb6a5fd78a930b961669c31516c3ff582bbab5306b99472241796f6ceec1b1' 
  AND token = 'tRJicnOug3FOW5JC6XxAXD2xrPPm1nu31sUj88PGvfc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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