SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68b5def6b60128b8d4a1f05bb85286b7fe177b117fd1a1c5432c2212e2930362' 
  AND token = 'gYHBOYsqy+VrxUMjc8/kUP4Bb+NpaqeJOJ8u+sYHMG4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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