SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f919ed58108b0eb541708a9768fad31ced33a0fa500fafb389d64e566d9ae042' 
  AND token = 'DEHKsaph1xJeImwT97nHvkauPTjN4eVm5PzaPbqBNig=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00053

JSON explain

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