SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2943d728d0899018fced9cdbe1a640a531d231464fb458bf8bb18d43ae3177f7' 
  AND token = 'z6U9ebheT9BN4d4JXFUXXoHeA7GhpPlDwhs0fUJbbXk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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