SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9c6c2461a021ede3404da15c82bed4ddd76ef539b8d5dbbc4207934fdfd861a8' 
  AND token = 'mkBn89bNGzzGpojPxoYsRYCJ/VxYsyVapIYH4KZbIRE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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