SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b5582ce4038409bca1eb0212faed2811e9517e12abe445821cc8abc412eed0e6' 
  AND token = '+l7MVQwAxUgYMmL6UABPLnIVZqyEtlqspTJ7qlUatHs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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