SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3a68cb8e64c8ce23994bba4efd67758489552aaeccbf292b4b09a73e9832071' 
  AND token = 'yeLEBrWaimPB1Dt/sLVcg4wSzVijpOHFHTDtlCTgNaI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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