SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ece975c04a290a0e9199fb38ea996a91bd42c1cbe2e9b6269184f7dc43fa5bb7' 
  AND token = 'mLNIVsEnmdY6tIdDI4/4W43WWHPo2+bU1e2jhsxVpew=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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