SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc978b3c72bfc367e4c836334e28b165c48d6dd81be7860d49596ecfd654c56f' 
  AND token = 't0tXCiWEdM6RYzmIGKn6bGhQamOcLLydmRhPEfFQ/ns=' 
  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"
    }
  }
}