SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9346cb5703843574e8188651fd7a581eca0485a47e610647712c625e9aa2b84' 
  AND token = 'UYWergOz4x09Su82xPEo4bCjzQ3dWspgWb+ePuGUq9E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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