SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '981db1d437d97dffa3b9e57be3ad941dcd3c20027e8f657336824bf5a1f44b97' 
  AND token = '6HoDuigrFNTBIGdUUVGSf0iyhyaucrFhd1cZVs49UfI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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