SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b146d0172c71aba28c292b1bc3ac7ef0982b457f223602718e0155f5e7583abd' 
  AND token = 'DScc+d5VkqR+Tfa5tIpIXPxC1yQnyDT4ggpRmhJ5lzI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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