SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd3e0b018603f34b25e3bc680575ef5947a6c72556cbdeb00a77d23414699ee56' 
  AND token = 'kxufUOdQKnKbTQjaFZSwf7Jw0zQ7gWExFe5UGMRMSfw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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