SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1a4e78e724695f7657bccab4429f4403f9afeb62ddca75715f52fa32f4360d9d' 
  AND token = 'njWN4XJU4GDweBrvBuLMf2Z/ScWvknUacLcsrXJJjkE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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