SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c5f77f89543dc60292aaef61fe9ba28bb01f796bb888b7c97c451d939f4290bd' 
  AND token = 't7zLvV+5MEYKIYt17GhELdbVmdGvUC+pzU/sDyFVSFE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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