SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4ae2a7703589ca676b61ac4c7bdd3de02415acd8dabf4ae8e0a3b8596f2c0796' 
  AND token = 'fPf0PWvPRoBYI+vhWwccLqg7zH/iPCU+z/HGaVXlZxQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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