SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '852deb8e08a707d8628baac005a6599675e021b531cb58ee85d5472d7b448d8b' 
  AND token = 'T6vcIYGKjcKmLd+ePgKp5T0XTGXg54dcxxxvYbargwo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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