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SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'c6ab9970a5a7cf2f3dab4ff81d368b67bf0b528faa98f6420a5e92b908032b70' 
  AND token = '2ync5p5femXHhPdxmggblFeAQAOrO6D3efv9IjVtGQg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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