SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5be4a1a48924edac30321ebfddd6d4075d16c3e9f28c4758999472a6fddd8b96' 
  AND token = '8BVfzTxmKW1XWhwnbSRy+6dvNKVR8bH8/VhcSTKujVM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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