SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6ded16ca84c2173d51052ff712a159587f5040d458c394ef988a2f27418598d' 
  AND token = 'XouAJbBn8dfl/UJktY7wuDsV5RuGhmSfS8r2BwIrCJs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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