SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4e0fefbf26257399805c2d5a01c611aa33375203802c504f59cb1a722f349cca' 
  AND token = 'VsHqA+Naj6h7Um6LKwQ5NwHpjzMw/YMq3kHWTRofDNg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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