SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b6719bacb3d76810ab49145040aaa985f19a26c2eea89bc0efcca3d03a895a7' 
  AND token = 'aT77IB+VoxHmwSeG+TfoJDsJOXABB2TWcjKo+T2D+nE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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