SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '346e01cd41c2efe0d32bfd242a3a09968ea6baa635789df5d65cee1a1c8b022c' 
  AND token = 'sK0lsrLkf68AcDubz98M+2B/QRgQKLeKoKjzYFlPZ/Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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