SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1a2087fa298ebc739c0758cea9d8d274348bb3b997fe90526260726178141ee2' 
  AND token = '9KGrP3dvgBxBxTolSHHWozW7SXf+NhSKfo+L/Gg1Xv0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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