SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c1f629205c73e0f370fad10aa0f7715f786b68574a8918a7be8cd4956eea9194' 
  AND token = 'xszmuwQ9UU9ohV3Xz00JBFyxlMLMbOzg9hR1HxsaNMk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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