SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '223bb37fe7171ef9636d7c853939b905801286af1ddb379a74ba7a7bc26f4564' 
  AND token = 'saQL+A2zjoFtTVL+ZaRagaG4z8JNyV51blKTsBSoj4o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00054

JSON explain

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