SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8499b853eea2ec132dfaa49043b4a2378933f97aa7ce9109d3867315bffa6edc' 
  AND token = '5nmelkPqvM7dGMF0e+4YDmNkfFATYi49JN4b687vQNw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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