SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6db18da402d5bb1073a79a99d18523ca8bca7caf487181cbdef7b02cda6e787b' 
  AND token = 'zSMu5pkbMC3lgsipzd6DdTtotCI9A0G5B9oCvgM1ehA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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