SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9ba588e1abda3982be602d84a6cb8984db835ce7fdd64038291ecadd389178c6' 
  AND token = 'gEBSrUFKFkf0ZZgxamSqP2Aytrh1Jn3kXLI3lCSlwMM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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