SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '44814654826695f116f209318956de3b6458f6d8f02dfa58091d8eb802aac7a2' 
  AND token = '5Yr4q+trIb1YLsVVVqrCGZ0EISRMP/wbq+nWBxLCGPI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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