SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cf6d3c0af784e0d7aa876870d871acbe9cfb710cd82213197200506598983a56' 
  AND token = '0l7fp8hMRUkgLPqpCERkBre3obuwjaemLRgI6e68mmY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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