SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5673fa1a5d3b6072efee1850db8125f713b5de6e4f32b6fa3476497bc4b3fb7d' 
  AND token = 'RHwiVZritwbzVuyf66OhLaTgwzxOWVOn3HI/LVBoKJU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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