SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68a70c95e45d2df776897b2cc8d383c2311172c018392bead2eccc32d53b481e' 
  AND token = 'YDEB7yo0OXL5raz2dryXvNoJWCzsAbyYNzltKy3TKTo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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