SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3959040872dfbb8de01bb0d1426980fb1da27c087a60243826169d49c3981df7' 
  AND token = 'ZpueENhUWunnPCCsUYccJmpNVtOpmOhOV3uGsa4Emrw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00058

JSON explain

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