SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6cfdf011be7351ef3d3608fd1bff7c38f62e9cb046367ddc98b75348e46e092' 
  AND token = 'gBavLTdbK8L1+J2LgKUCiSXvTkj/BUH5PnreuYRK4fo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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