SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bd27afb5b47926569383aff790744744c41108c31c3940d225c6bf6acc43136c' 
  AND token = 'oQb68RKTJGyJqpuyKzhgsUj3jO/SubX7hvjkXGuoLj0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}