SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a591c44622e944428bf98fdffbc4430e4c1b94cf7d968383b2e6decb1f09933' 
  AND token = '5ZlC5xCDizqu0RamhqHhUNTDP8ORYUh7EVRJKlQCtm4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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