SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '738ad494ea621b35e57a7bbea380766c0885ecd9209ed4cf1b544a678101a7fb' 
  AND token = 'jx01jTmHHZ/soJ9gJAQhuMmMqVn/s+k97kiAtMSUgvg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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