SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc7ba1964445cd788a0cf8d4cf5a9b9dbfdfc739cab2468078a014f099302550' 
  AND token = 'vv2A+htpUASnv5YqwUZIKyxdGGXKnmvIqotx+LR+Loc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00052

JSON explain

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