SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3ddcca5ba215df34efd1a514b6cb135cd24396877948498057f2793f2030279a' 
  AND token = 'GSoxDgLQWMMy8VlsFnfe1JL2mlbQwEOmG/Qhup+1bhc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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