SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68234dc8e0bd30294978efba73ddf6abd5135ebb12e5a26e0028faf75432d0d4' 
  AND token = 'KZuRtayb/NPcQcKw6xk6p82bBqd96E+488Xcm49UI8k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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