SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '509225d21b19c395082b1515189e1402925c68dd026036281c59079c5db77071' 
  AND token = 'hD5eMvIlaA29rLygHTu1gBLb4tSADANrzrspP4hWByQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}