SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '28f9fb0dd7a2dbd659fc359933d20f042aced30aead95056b0e292a12919e996' 
  AND token = 'KREdVqwmiZUzhH8PHFEW1himF0QuPC7i8LBHg18oP0M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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