SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a404bcb6f83c77f0304e8f62c1881177761aefeeeb9866d633940abbdae44f43' 
  AND token = 'rhrfZDAvkO9ucJVKFQ9G9M4Wi3enmWyaUFmM3PeQaJc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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