SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e725cb4cefc55339b7490150202c737002fe04e723baacf2dd124ae074226ed3' 
  AND token = 'Wrck+DXkBrFGTpCOIO9g66XcuSUE0VB8uLFOfSPvlT4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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