SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a316860991609e826344ccb3c7272253eb816dccd7eb39aaa5815540ce6428f3' 
  AND token = '2PU5d3yZpxLCPUgTG3jEuGlkGlzMTrX0GTKZlTu2Irc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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