SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd51db5f7dfdeca5677bae43f2aa8c41456d6ccf1daacddc77219e2d131b64319' 
  AND token = 'uwulwocdhAFMUM8p0JyGdQB3T4bjo6vTBIdPEFF9OLU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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