SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6dae96b77dc7418b21baff457fd047872855bd8903aac1dbc1a1f3c64009caf9' 
  AND token = 'Hkkjmmic9vctqihtG3Vlwz9BMNGLQLrvhtGTvoNu/EY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00055

JSON explain

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