SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8fe9f27b22006a599361641bbe1a9fa7a1dc0cb45af18eb2781398168685b7c6' 
  AND token = 'AQ29DXwXSj/qd395BI1tLngG5PKBZuwlL1FO3fHudT4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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