SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e3e188c76a4f292d2ff951490ce1196c3d4ef9fc79c5a48325a5dc5b9c68f92a' 
  AND token = 'RekFjFrheDpAoMiO6s+FB9hVeESogwhuosCAESdBXuY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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