SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '512f0783eb13350b9ad49ba7469681f36945b2c172feaec7ac247bbdda6dd541' 
  AND token = 'EOg8/YLSXG6G7g5Sn5vtQpK4SODGR+ZxOfOfpSVFboQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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