SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4d76190480e62d76d58e9d11e7e8d13d87b9322a8fc1ce13daa386cc729401e' 
  AND token = 'eVOHg5S39GfiofIVXxVpsyHb7PQYYxlh8D/tmsqRX3s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}