SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ad3e918114c319745697f76f729b4a0b43ffff2ba3a3467b9084ae4af5e8e948' 
  AND token = 'SSG4gUwfagfdIyaXghJsjbAzlnvFuTPY8O9np5ld+/U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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