SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a41fba47678651b32b89571090b4b250f89b1ddf42800bfc903910e4490706f3' 
  AND token = '6/dGRf+iOwI2co8HgonZVyxkpgYfuGlChzi/o3NbfB8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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