SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b816aa1196cb7c59fcd6d5c6efc4ca55fd513cf28bddf4caf3448633d6fbedd1' 
  AND token = 'GiwrtSm1t/ATfpoWdM4MGBNSWIuaUWVJnoG/RXfBibM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

JSON explain

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