SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b0d521c4b634edcbc2b053a4456b21af8a99b2da451b96f45b757070954849ba' 
  AND token = 'F6p9sEJRZ/vY2lhPOA1XKArV+6SYStMRKUNqdOwfsnc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00085

JSON explain

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