SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '261e46232c95d9e3df459150b005daacff7d5e7919d1b1321f4be764a8d32a87' 
  AND token = 'wxnNmWTgx3TnDTyG0JbSxGQ759qYBDoq4vw+hHxNSsc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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