SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '042753f270354c56bdcc3decd8ca26363409c534f002fb80284e0c2255f6d680' 
  AND token = 'nLJSKCUm+wt9CgdsU27eCkujb0UAEpdPfVcbatVeek4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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