SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd3b50532a6f2e445e48b2f47b084e7672b9e1d2e40c22219373c2354d0a73621' 
  AND token = '7p6PRiA+FxMqsgGcGyk2CTmFqQi5BbnILyc1iFF/UeQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00062

JSON explain

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