SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '997fa06ab704ec66930c01266f965928950f96d84c73488ab33b97b03d3468c8' 
  AND token = 'Et/tmgAfMDgKrD31RWXI7EtT0V4CFexTe0mrZmj46mA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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