SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'd2a077f1fbd4fce4c3f1040eb4108acb1c90241dbcf0ddd05ea2636789da74e2' 
  AND token = 'Qj1NKTMct4SVAmujh0ph/bL55mYW/dJ7g6bEQ9Fo53k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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