SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8e42ba13e361015e6fb89eaa39bea88070d7dbb284a4ccd93d814ee5be01c61' 
  AND token = 'LHBtiwM4h6AMf+BCT1LKjodn4HruixuMnGzbWJ/m9vI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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