SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a9ffbe4b6c0449761aed479ece1ceb9c6884974d5612026cf2a807cac89d456e' 
  AND token = 'eLYzvGRGFJHw7kwtuhG7ReiUhV/ZPrru5hPv83vd/gg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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