SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4138669aa517ff96bacf45062a79da719d4cdf6a90c6dd34d40207b57de8da82' 
  AND token = 'Ai2ycpl0TKpmQnN4568R4n57ZyIMSBRdso6xnveLRps=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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