SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4921e5081c6c43fbb53861c826074049da0f192eced2194179a7cfb708692481' 
  AND token = 'q7V7DNMC03sv2cS0us7zLx2QITgMNX2LRWd/W9tfFrw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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