SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd66b6bf370dc4b8261073f92a037b60d88e07b10484de00d6a75081f46236275' 
  AND token = '73kZXtV/xOhubF4S0dSAI2hUJFkwnbl0YidByRAH1Gc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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