SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b98c5acaba5246c6b1c1300c80992574c478ddc24335b7120dee1b616cb8246a' 
  AND token = 'ddf7RMkyo9mLBliZbbWsDttoULdXds7jFevPqOpke7I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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