SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cb0e8aaada503f5e725bc3c9d0781456195ba8d08423f45fffcc4e8e4be88c7d' 
  AND token = 'FBSt4swRW34VeeDsgqPhU3zlhBmvgfE3FUVem4dT3Zs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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