SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '94779f47c544ee1114b7a09515bfb99026de6487eee43ce0e3938ff58aa8f4f8' 
  AND token = 'KT0wmhWGFUIBV9gPaDuFZL6huBHvhJ9sPuKiAwxgKNY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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