SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7cfaff9bbd50343f4c7820167c4c7e77485e5e468b703dc73fb83960d4b1a1c8' 
  AND token = 'gxStfy46gwBDTR5/rsXkUZAMhayIh1KjZDvlQNifHuY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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