SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6bdfee4d3e4262a1fadcf12294c19ab429462f50f6920c617b719663070d25d9' 
  AND token = 'Hs39zTz4BU2HOMbw/SHiE2l3Wv+cST2aKAZ/GdFm5I0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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