SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ea3c4c0f842d45fa8804d5b45e70465084ecfbdde7139e321bd898c982c6b26d' 
  AND token = 'zadb4lCLTjYk0eRvgwLpOXkVqVztyVCPhUH3iVaDhDY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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