SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42f40dd7ae5ef823c89150a8f8df5cd58e1a898ad3007b118178051f532315be' 
  AND token = 'jHKz0mwXKujj+bv55Le1d3w/7Ae+sNnScnepG5W5Dyg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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