SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd51fd3387f2f01294d8a98ca0bfeb0146cbbd0272362f00e9d079d94b7fba9a8' 
  AND token = 'oKTtxO2jvlj/pB6GUJeVCEym/zDNHuF4NrSWPWWwfhA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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